This invention relates to marine seismic data acquisition and processing and more particularly to three dimensional processing.
In acquiring three dimensional marine seismic data, equipment problems and noise can cause unacceptable data to be received at locations along a seismic survey. If this unacceptable data is not detected, serious quality problems in the processed data will occur. Since many of the problems that occur during seismic data acquisition are not detected until after the data is transported to a land-based processing center and the seismic recording vessel has left the survey area, returning to re-acquire the data is very time-consuming and expensive. Accordingly, there is a need to detect errors in the data as it is being acquired.
Many of the problems cannot be detected until the raw data received from the seismic receivers is migrated or imaged. As conducted currently and in the past, this is a very time-intensive process. Much discussion among those published in the area revolves around dealing with the inaccuracy of using time migration and the need to perform accurate velocity analysis in order to have well-imaged data.
Velocity analysis is known to be a time consuming iterative process, requiring some months of work to perform. As noted, the velocity analysis requires a starting assumption for the work, which is revised after the person conducting the velocity analysis sees a set of migrated data. This need to see migrated data before being able to conduct proper velocity analysis makes the iterative process quite long.
Additionally, interpretation of data, independent of velocity analysis and depth migration, currently must wait for depth migration. Since the time from acquisition to fully migrated data is about three to four months, the seismic data is not available in time to modify drilling or production activities in the acquisition area.
Accordingly, there is a need for a more real-time method of reviewing the quality of data and to reduce the number of iterations needed in velocity analysis before performing depth migration, as well as to provide a real-time interpretation tool for drilling and field management.